College of American Pathologists

  Press Release


Published on August 5, 2009

Contact: Carolyn Barth
Phone: 800-323-4040, ext.7185

Although pathologists say the risk of developing a serious West Nile virus is low, you should still take measures to protect your family’s health

NORTHFIELD, ILL. — Mosquito bites are irritating—they cause swelling and itching. But when the mosquito that bit you carries the West Nile Virus (WNV), they can also be dangerous. In 2008, 1356 cases were reported throughout the United States, according to the Center of Disease Control. With this year’s rain throughout the country, the number of cases could grow.

Experts believe WNV is established as a seasonal epidemic in North America, which flares up in the summer and continues into the fall. Mosquitoes become infected when they feed on a bird contaminated with WNV. Humans are then infected when bitten by a diseased mosquito.

“Even if you are bitten by a diseased mosquito, your risk of becoming seriously ill is low,” said Shelby D. Melton, MD, a pathologist in Dallas, Texas. “Most people infected with West Nile Virus have no symptoms. They don’t even realize they’ve had the disease.”

Pathologists are physicians who examine tissues and cells to identify and diagnose disease. Through a simple blood test, they can determine if a patient has WNV.

Of the small percentage of people who have symptoms, most will be mild and include fever, headache and body aches. People typically develop symptoms between three and 14 days after they are bitten by an infected mosquito.

However, about 1 in 150 people infected with the WNV will develop severe illness such as West Nile Encephalitis or Meningitis. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks and neurological effects may be permanent.

“The populations at the greatest risk are people with weakened immune systems and those over age 50,” said Dr. Melton. “If you or a family member experience symptoms of WNV, it’s best to seek medical attention immediately.”

West Nile Virus activity is prevalent in nearly all parts of the country, and everyone should take steps to minimize their risk of infection. A two-step approach is the most effective way to reduce the chances of becoming infected with WNV: eliminate mosquito-breeding areas and prevent mosquito bites.

    To reduce the mosquito breeding potential in your yard:
  • Keep your rain gutters clean. Culex mosquitoes, the breed most commonly infected with WNV, like to breed in waterlogged, decaying leaves.
  • Change the water in birdbaths, dog bowls, wading pools, etc. at least every two days.
  • Clean your yard of toys and buckets where water may collect.
  • Culex mosquitoes like to live in houses. Check windows and screens for holes.
    To avoid mosquito bites:
  • Regularly apply insect repellents containing DEET; apply even more frequently if you are sweating or getting wet.
  • Apply mosquito repellent on exposed skin and on clothes.
  • Avoid going outside when mosquitoes are most active: dawn, dusk and throughout the evening.
  • If you do go outdoors, wear light-colored, loose-fitting clothing that covers as much of your skin as possible.
  • Avoid perfumes or after-shaves.
  • Replace outdoor lights with yellow “bug” lights.

It should be noted that products containing DEET can safely be applied to children as young as two months. However, when applying the repellent, avoid the eyes, mouths and hands. Also, consumers should be aware that products with 30 percent DEET are effective for up to five hours. As the amount of DEET decreases in a product, so does the time it is effective.

“Enjoy the outdoors this summer, and remember the easiest and best way to avoid West Nile Virus is protection from mosquito bites,” said Dr. Melton.

The College of American Pathologists (CAP) is a medical society serving about 17,000 physician members and the laboratory community throughout the world. It is the world’s largest association composed exclusively of pathologists and is widely considered the leader in laboratory quality assurance. The CAP is an advocate for high quality and cost-effective patient care.